One request: can we get a physical description of Siobhan, for those of us who haven't read the books? There are various references to her being "huge" and I'm not sure exactly how to construct that, mentally.

From Luminosity, Book 1:

Siobhan was a brunette, with a short and well-maintained haircut. She was very tall and broad, and she moved forward to greet us with an undulating smoothness that I considered trying to emulate before deciding that its impressiveness depended on her size. I wondered if she could beat Emmett in a fight and was unsure. She was barefoot, like the others, and they were all dressed in simple outdoor wear.